Commenting using the user name

I am following 2 blogs: one created on WordPress and one created on blogger.com. I can comment on one but when I try to comment on the blogger.com blog, it won't accept my username. The response says that I don't own that username. What am I doing wrong?
Blog url: http://cinderworld.wordpress.com/

It's not you. It's how Blogger software is set up. Trying to post comments on Blogger blogs is a drag. Open ID fails more often than it works and blogspot software thinks we all have a single username here at wordpress.com and a single blog by the same name. So if we have a domain or more than one blog registered under the same WordPress.com username trying to comment becomes a nightmare. Unless the blogger chooses to enable commenters to post with a username and URL on their Blogger blog it's next to impossible to leave a comment. The only workaround is to register a Blogger blog which will allow you to comment but your username will not be linked to your WordPress.com blog when you do.